I think its always been around. It might be more common to see it without further qualification (IE, "It's blue, isn't it?"), possibly because of the popularity of short-form content, but I don't think its a new thing.

At least from the example you gave, it is a question more than a statement. They're not correcting you so much as questioning your answer and offering what they think it really is. Basically, skipping the filler in asking "Are you sure its purple, not blue?"

Its a slightly older image that I've had sitting on my drive, but I believe I used the Deliberate model for Stable Diffusion, with the A1111 web ui and the Controlnet Addon to create/use a depth map.

Obviously not the best, with some of the usual AI issues, but I'm still fairly happy with the result given the aged graphics of the original map.